Andreas Kay

Low cost photovoltaic modules based on dye sensitized nanocrystalline titanium dioxide and carbon powder

A new type of photovoltaic module based on monolithically series connected dye sensitized photoelectrochemical cells is described. Each solar cell element consists of three porous layers on a transparent conducting substrate, namely a photoelectrode of dye sensitized nanocrystalline TiO2 (anatase), a spacer of electrically insulating, light reflecting particles of TiO2 (rutile), and a counterelectrode of graphite powder and carbon black. The pores of these layers are filled with a redox electrolyte containing iodide for hole transport between photo- and counterelectrode. The monolithic series connection on the transparent conducting substrate, e.g., SnO2 coated glass, is achieved by simple overlap of each carbon counterelectrode with the back contact of the adjacent photoelectrode. Such modules may be produced in a continuous non-vacuum process by simple printing techniques. In this paper we present the first results on energy conversion efficiency and long term stability obtained with this new type of solar cell.

Preparation of TiO2 (anatase) films on electrodes by anodic oxidative hydrolysis of TiCl3

Ti(IV) oxide films were deposited on SnO2 (F-doped) and metallic (Pt, Au, Ti) electrodes by anodic oxidative hydrolysis of acidic aqueous TiCl3 solutions. The films are uniform in thickness, and have the anatase structure after annealing at 450°C. They show the expected electrochemical and photoelectrochemical activity of semiconducting n-TiO2 (anatase). Thin films supported by a rough polycrystalline anatase electrode were spectrally sensitized to higher wavelengths by adsorption of RuL2(μ-(NC)Ru(CN)(bpy)2)2 (L = 2, 2′-bipyridine-4,4′-dicarboxylic acid, bpy = 2,2′-bipyridine). The performance of an I-/I2 regenerative photocell based on a thus prepared TiO2 photoanode is considerably improved in comparison with that employing a photoanode unmodified by electrodeposition.

LiMn0.8Fe0.2PO4: An Advanced Cathode Material for Rechargeable Lithium Batteries†

Keywords: cathode materials ; lithium batteries ; nanoparticles ; surface chemistry ; thermal stability ; Performance ; Electrodes Reference EPFL-ARTICLE-159236doi:10.1002/anie.200903587View record in Web of Science Record created on 2010-11-30, modified on 2017-05-12

Improving the Electrochemical Activity of LiMnPO4 Via Mn-Site Substitution

HPL SA report the modification of the electrochemical performance of lithium manganese phosphate (LiMnPO4) via Mn-site bivalent substitution. Manganese (10%) is substituted with iron, nickel, magnesium, or zinc. These substituents are shown via an X-ray to form solid solutions. The choice of substituent is demonstrated to have a strong influence on the electrochemical performance. The optimum performance improvement was achieved when 10% of Fe is substituted. This is ascribed to a smaller crystallite and a higher electronic conductivity observed in this material: Presumably Fe plays a role in hindering the crystallite growth and in increasing the carriers transportation. Electronic structures were calculated by density function theory to understand the different influences of substitute cations.

Mediator Transport in Multilayer Nanocrystalline Photoelectrochemical Cell Configurations

Reference LPI-ARTICLE-1999-019doi:10.1149/1.1391698View record in Web of Science Record created on 2006-02-21, modified on 2017-05-12

Nanocrystalline TiO2 Electrodes Exhibiting High Storage Capacity and Stability in Rechargeable Lithium Batteries

Nanocrystalline TiO2 films were explored for the first time as electrode material for a rechargeable lithium intercalation cell, i.e., Li/LiCF3SO3